Visible light sensor configured for glare detection and controlling motorized window treatments

ABSTRACT

A sensor may detect glare from a recorded image and a shade position of a motorized window treatment may be controlled based on the position of the detected glare in the image. A luminance of a pixel may be calculated in an image and a glare condition may be detected based on the luminance of the pixel. For example, the sensor may start at a first pixel in a bottom row of pixels and step through each of the pixels on the bottom row before moving to a next row of pixels. When the sensor detects a glare condition, the sensor may cease processing the remaining pixels of the image. The sensor may calculate a background luminance of the image by reordering the pixels of the image from darkest to lightest and calculating the luminance of a pixel that is a predetermined percentage from the darkest pixel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Patent Application No. 62/466,696, filed Mar. 3, 2017, which is hereby incorporated by reference in its entirety.

BACKGROUND

A user environment, such as a residence or an office building, for example, may be configured using various types of load control systems. A lighting control system may be used to control the lighting loads providing artificial light in the user environment. A motorized window treatment control system may be used to control the natural light provided to the user environment. An HVAC system may be used to control the temperature in the user environment.

Each load control system may include various control devices, including input devices and load control devices. The load control devices may receive digital messages, which may include load control instructions, for controlling an electrical load from one or more of the input devices. The load control devices may be capable of directly controlling an electrical load. The input devices may be capable of indirectly controlling the electrical load via the load control device.

Examples of load control devices may include lighting control devices (e.g., a dimmer switch, an electronic switch, a ballast, or a light-emitting diode (LED) driver), a motorized window treatment, a temperature control device (e.g., a thermostat), an AC plug-in load control device, and/or the like. Examples of input devices may include remote control devices, occupancy sensors, daylight sensors, glare sensors, color temperature sensors, temperature sensors, and/or the like. Remote control devices may receive user input for performing load control. Occupancy sensors may include infrared (IR) sensors for detecting occupancy/vacancy of a space based on movement of the users. Daylight sensors may detect a daylight level received within a space. Color temperature sensor determines the color temperature within a user environment based on the wavelengths and/or frequencies of light. Temperature sensors may detect the current temperature of the space. Window sensors (e.g., glare sensors) may be positioned facing outside of a building (e.g., on a window or exterior of a building) to measure the total amount of natural light detected outside the building and/or detect glare conditions.

Some prior art load control systems have controlled motorized window treatments to prevent glare conditions inside of the building (e.g., glare conditions caused by direct sunlight shining into the building). The load control system may include a system controller for determining positions to which to control shade fabric of the motorized window treatments to prevent glare conditions based on the predicted location of the sun (e.g., using the present time of the day and year, the location and/or orientation of the building, etc.). The load control system may automatically control the motorized window treatments throughout the day according to the estimated positions of the sun. The load control system may also include window sensors that are configured to detect low light conditions (e.g., on cloudy days) and/or high light conditions (e.g., on extremely bright days) to enable the system controller to override the automatic control of the motorized window treatments on cloudy days and bright days. However, such load control systems require complicated configuration procedure and advanced system controller to operate appropriately. These systems are also performing estimation of daylight glare based on known conditions (e.g., the present time of the day and year, the location and/or orientation of the building, etc.) and/or a total amount of daylight sensed at the location of a given sensor. Examples of such a load control system is described in commonly-assigned U.S. Pat. No. 8,288,981, issued Oct. 16, 2012, entitled METHOD OF AUTOMATICALLY CONTROLLING A MOTORIZED WINDOW TREATMENT WHILE MINIMIZING OCCUPANT DISTRACTIONS, the entire disclosure of which is hereby incorporated by reference.

SUMMARY

A sensor (e.g., a visible light sensor) and/or a system controller may process an image to determine the position of a glare source and control motorized window treatments to prevent the glare source from affecting an occupant of a room. The sensor (e.g., a visible light sensor) and/or a system controller may process the pixels of the image to determine whether a glare condition exists. The sensor and/or system controller may begin processing a pixel at a portion of the image (e.g., the bottom or top of the image). The sensor and/or system controller may begin processing pixels at a bottom or top row of pixels in an image and compare the luminance of the pixels to one or more thresholds to determine if a glare condition (e.g., an absolute glare condition and/or a relative glare condition) exists. The sensor and/or system controller may stop processing the image after determining that a glare condition exists, which may simplify and/or expedite processing of the image to identify a glare condition.

After determining that a glare condition exists, the sensor and/or system controller may determine a profile angle for the glare source. The sensor and/or system controller may use the profile angle to identify the position to which a shade level may be controlled at one or more motorized window treatments to prevent the glare condition from affecting the occupant of the room.

As described herein, a sensor for detecting glare may comprise a visible light sensing circuit configured to record one or more images, and a control circuit configured to calculate a respective luminance of multiple pixels of an image (e.g., a non-warped image) and detect a glare condition in response to the luminance of at least one of the pixels. While calculating the respective luminance of each of the multiple pixels, the control circuit may be configured to start at a first pixel on a bottom row of pixels of the non-warped image and step through each of the multiple pixels on the bottom row before stepping up to a next row of pixels immediately above the bottom row. When the control circuit detects the glare condition, the control circuit may cease processing the non-warped image by not calculating the respective luminance of each of the remaining pixels of the non-warped image.

In addition, the control circuit may be configured to calculate the background luminance of the image by reordering the pixels of the image from darkest to lightest and calculating the luminance of a pixel that is a predetermined percentage of the distance from the darkest pixel to the lightest pixel. The control circuit may be configured to detect a glare condition if the ratio of the luminance of a specific pixel to the background luminance is greater than a predetermined contrast threshold. Though the sensor may be described as performing image processing for detecting glare conditions for controlling a shade level of a motorized window treatment, a system controller or another image processing device may perform similar functions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simple diagram of an example load control system having visible light sensors.

FIG. 2 is a side view of an example space having a visible light sensor.

FIG. 3 is a simplified block diagram of an example visible light sensor.

FIG. 4 shows a flowchart of an example glare detection procedure.

FIGS. 5A and 5B shows flowcharts of example glare detection procedures that may be executed by a control circuit of a visible light sensor.

FIG. 6 shows a flowchart of a simplified procedure for determining a background luminance.

FIG. 7A shows a simplified sequence diagram of an example glare detection procedure that may be executed by a visible light sensor and a motorized window treatment.

FIG. 7B shows a simplified sequence diagram of an example glare detection procedure that may be executed by a visible light sensor, a system controller, and a motorized window treatment.

FIG. 8 is a simplified example of a non-warped image used for glare detection.

FIG. 9 is a block diagram of an example system controller.

FIG. 10 is a block diagram of an example control-target device.

DETAILED DESCRIPTION

FIG. 1 is a simple diagram of an example load control system 100 for controlling the amount of power delivered from an alternating-current (AC) power source (not shown) to one or more electrical loads. The load control system 100 may be installed in a room 102 of a building. The load control system 100 may comprise a plurality of control devices configured to communicate with each other via wireless signals, e.g., radio-frequency (RF) signals 108. Alternatively or additionally, the load control system 100 may comprise a wired digital communication link coupled to one or more of the control devices to provide for communication between the load control devices. The control devices of the load control system 100 may comprise a number of control-source devices (e.g., input devices operable to transmit digital messages in response to user inputs, occupancy/vacancy conditions, changes in measured light intensity, etc.) and a number of control-target devices (e.g., load control devices operable to receive digital messages and control respective electrical loads in response to the received digital messages). A single control device of the load control system 100 may operate as both a control-source and a control-target device.

The control-source devices may be configured to transmit digital messages directly to the control-target devices. In addition, the load control system 100 may comprise a system controller 110 (e.g., a central processor or load controller) operable to communicate digital messages to and from the control devices (e.g., the control-source devices and/or the control-target devices). For example, the system controller 110 may be configured to receive digital messages from the control-source devices and transmit digital messages to the control-target devices in response to the digital messages received from the control-source devices. The control-source and control-target devices and the system controller 110 may be configured to transmit and receive the RF signals 108 using a proprietary RF protocol, such as the ClearConnect® protocol. Alternatively, the RF signals 108 may be transmitted using a different RF protocol, such as, a standard protocol, for example, one of WIFI, ZIGBEE, Z-WAVE, KNX-RF, ENOCEAN RADIO protocols, or a different proprietary protocol.

The load control system 100 may comprise one or more load control devices, e.g., a dimmer switch 120 for controlling a lighting load 122. The dimmer switch 120 may be adapted to be wall-mounted in a standard electrical wallbox. The dimmer switch 120 may comprise a tabletop or plug-in load control device. The dimmer switch 120 may comprise a toggle actuator (e.g., a button) and an intensity adjustment actuator (e.g., a rocker switch). Actuations (e.g., successive actuations) of the toggle actuator may toggle (e.g., turn off and on) the lighting load 122. Actuations of an upper portion or a lower portion of the intensity adjustment actuator may respectively increase or decrease the amount of power delivered to the lighting load 122 and thus increase or decrease the intensity of the receptive lighting load from a minimum intensity (e.g., approximately 1%) to a maximum intensity (e.g., approximately 100%). The dimmer switch 120 may comprise a plurality of visual indicators, e.g., light-emitting diodes (LEDs), which may be arranged in a linear array and are illuminated to provide feedback of the intensity of the lighting load 122. Examples of wall-mounted dimmer switches are described in greater detail in U.S. Pat. No. 5,248,919, issued Sep. 28, 1993, entitled LIGHTING CONTROL DEVICE, and U.S. Pat. No. 9,676,696, issued Jun. 13, 2017, entitled WIRELESS LOAD CONTROL DEVICE, the entire disclosures of which are hereby incorporated by reference.

The dimmer switch 120 may be configured to wirelessly receive digital messages via the RF signals 108 (e.g., from the system controller 110) and to control the lighting load 122 in response to the received digital messages. Examples of dimmer switches operable to transmit and receive digital messages is described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2009/0206983, published Aug. 20, 2009, entitled COMMUNICATION PROTOCOL FOR A RADIO-FREQUENCY LOAD CONTROL SYSTEM, the entire disclosure of which is hereby incorporated by reference.

The load control system 100 may comprise one or more remotely-located load control devices, such as a light-emitting diode (LED) driver 130 for driving an LED light source 132 (e.g., an LED light engine). The LED driver 130 may be located remotely, for example, in or adjacent to the lighting fixture of the LED light source 132. The LED driver 130 may be configured to receive digital messages via the RF signals 108 (e.g., from the system controller 110) and to control the LED light source 132 in response to the received digital messages. The LED driver 130 may be configured to adjust the color temperature of the LED light source 132 in response to the received digital messages. Examples of LED drivers configured to control the color temperature of LED light sources are described in greater detail in commonly-assigned U.S. Pat. No. 9,538,603, issued Jan. 3, 2017, entitled SYSTEMS AND METHODS FOR CONTROLLING COLOR TEMPERATURE, the entire disclosure of which is hereby incorporated by reference. The load control system 100 may further comprise other types of remotely-located load control devices, such as, for example, electronic dimming ballasts for driving fluorescent lamps.

The load control system 100 may comprise a plug-in load control device 140 for controlling a plug-in electrical load, e.g., a plug-in lighting load (such as a floor lamp 142 or a table lamp) and/or an appliance (such as a television or a computer monitor). For example, the floor lamp 142 may be plugged into the plug-in load control device 140. The plug-in load control device 140 may be plugged into a standard electrical outlet 144 and thus may be coupled in series between the AC power source and the plug-in lighting load. The plug-in load control device 140 may be configured to receive digital messages via the RF signals 108 (e.g., from the system controller 110) and to turn on and off or adjust the intensity of the floor lamp 142 in response to the received digital messages.

Alternatively or additionally, the load control system 100 may comprise controllable receptacles for controlling plug-in electrical loads plugged into the receptacles. The load control system 100 may comprise one or more load control devices or appliances that are able to directly receive the wireless signals 108 from the system controller 110, such as a speaker 146 (e.g., part of an audio/visual or intercom system), which is able to generate audible sounds, such as alarms, music, intercom functionality, etc.

The load control system 100 may comprise one or more daylight control devices, e.g., motorized window treatments 150, such as motorized cellular shades, for controlling the amount of daylight entering the room 102. Each motorized window treatments 150 may comprise a window treatment fabric 152 hanging from a headrail 154 in front of a respective window 104. Each motorized window treatment 150 may further comprise a motor drive unit (not shown) located inside of the headrail 154 for raising and lowering the window treatment fabric 152 for controlling the amount of daylight entering the room 102. The motor drive units of the motorized window treatments 150 may be configured to receive digital messages via the RF signals 108 (e.g., from the system controller 110) and adjust the position of the respective window treatment fabric 152 in response to the received digital messages. The load control system 100 may comprise other types of daylight control devices, such as, for example, a cellular shade, a drapery, a Roman shade, a Venetian blind, a Persian blind, a pleated blind, a tensioned roller shade system, an electrochromic or smart window, and/or other suitable daylight control device. Examples of battery-powered motorized window treatments are described in greater detail in U.S. Pat. No. 8,950,461, issued Feb. 10, 2015, entitled MOTORIZED WINDOW TREATMENT, and U.S. Pat. No. 9,488,000, issued Nov. 8, 2016, entitled INTEGRATED ACCESSIBLE BATTERY COMPARTMENT FOR MOTORIZED WINDOW TREATMENT, the entire disclosures of which are hereby incorporated by reference.

The load control system 100 may comprise one or more temperature control devices, e.g., a thermostat 160 for controlling a room temperature in the room 102. The thermostat 160 may be coupled to a heating, ventilation, and air conditioning (HVAC) system 162 via a control link (e.g., an analog control link or a wired digital communication link). The thermostat 160 may be configured to wirelessly communicate digital messages with a controller of the HVAC system 162. The thermostat 160 may comprise a temperature sensor for measuring the room temperature of the room 102 and may control the HVAC system 162 to adjust the temperature in the room to a setpoint temperature. The load control system 100 may comprise one or more wireless temperature sensors (not shown) located in the room 102 for measuring the room temperatures. The HVAC system 162 may be configured to turn a compressor on and off for cooling the room 102 and to turn a heating source on and off for heating the rooms in response to the control signals received from the thermostat 160. The HVAC system 162 may be configured to turn a fan of the HVAC system on and off in response to the control signals received from the thermostat 160. The thermostat 160 and/or the HVAC system 162 may be configured to control one or more controllable dampers to control the air flow in the room 102. The thermostat 160 may be configured to receive digital messages via the RF signals 108 (e.g., from the system controller 110) and adjust heating, ventilation, and cooling in response to the received digital messages.

The load control system 100 may comprise one or more other types of load control devices, such as, for example, a screw-in luminaire including a dimmer circuit and an incandescent or halogen lamp; a screw-in luminaire including a ballast and a compact fluorescent lamp; a screw-in luminaire including an LED driver and an LED light source; an electronic switch, controllable circuit breaker, or other switching device for turning an appliance on and off; a plug-in load control device, controllable electrical receptacle, or controllable power strip for controlling one or more plug-in loads; a motor control unit for controlling a motor load, such as a ceiling fan or an exhaust fan; a drive unit for controlling a motorized window treatment or a projection screen; motorized interior or exterior shutters; a thermostat for a heating and/or cooling system; a temperature control device for controlling a setpoint temperature of an HVAC system; an air conditioner; a compressor; an electric baseboard heater controller; a controllable damper; a variable air volume controller; a fresh air intake controller; a ventilation controller; a hydraulic valves for use radiators and radiant heating system; a humidity control unit; a humidifier; a dehumidifier; a water heater; a boiler controller; a pool pump; a refrigerator; a freezer; a television or computer monitor; a video camera; an audio system or amplifier; an elevator; a power supply; a generator; an electric charger, such as an electric vehicle charger; and an alternative energy controller.

The load control system 100 may comprise one or more input devices, e.g., such as a remote control device 170, a first visible light sensor 180 (e.g., a room sensor), and a second visible light sensor 182 (e.g., a window sensor). The input devices may be fixed or movable input devices. The system controller 110 may be configured to transmit one or more digital messages to the load control devices (e.g., the dimmer switch 120, the LED driver 130, the plug-in load control device 140, the motorized window treatments 150, and/or the thermostat 160) in response to the digital messages received from the remote control device 170 and the visible light sensors 180, 182. The remote control device 170 and the visible light sensors 180, 182 may be configured to transmit digital messages directly to the dimmer switch 120, the LED driver 130, the plug-in load control device 140, the motorized window treatments 150, and the temperature control device 160.

The remote control device 170 may be configured to transmit digital messages via the RF signals 108 to the system controller 110 (e.g., directly to the system controller) in response to an actuation of one or more buttons of the remote control device. For example, the remote control device 170 may be battery-powered. The load control system 100 may comprise other types of input devices, such as, for example, temperature sensors, humidity sensors, radiometers, cloudy-day sensors, shadow sensors, pressure sensors, smoke detectors, carbon monoxide detectors, air-quality sensors, motion sensors, security sensors, proximity sensors, fixture sensors, partition sensors, keypads, multi-zone control units, slider control units, kinetic or solar-powered remote controls, key fobs, cell phones, smart phones, tablets, personal digital assistants, personal computers, laptops, timeclocks, audio-visual controls, safety devices, power monitoring devices (e.g., such as power meters, energy meters, utility submeters, utility rate meters, etc.), central control transmitters, residential, commercial, or industrial controllers, and/or any combination thereof.

The system controller 110 may be coupled to a network, such as a wireless or wired local area network (LAN), e.g., for access to the Internet. The system controller 110 may be wirelessly connected to the network, e.g., using Wi-Fi technology. The system controller 110 may be coupled to the network via a network communication bus (e.g., an Ethernet communication link). The system controller 110 may be configured to communicate via the network with one or more network devices, e.g., a mobile device 190, such as, a personal computing device and/or a wearable wireless device. The mobile device 190 may be located on an occupant 192, for example, may be attached to the occupant's body or clothing or may be held by the occupant. The mobile device 190 may be characterized by a unique identifier (e.g., a serial number or address stored in memory) that uniquely identifies the mobile device 190 and thus the occupant 192. Examples of personal computing devices may include a smart phone (for example, an iPhone® smart phone, an Android® smart phone, or a Blackberry® smart phone), a laptop, and/or a tablet device (for example, an iPad® hand-held computing device). Examples of wearable wireless devices may include an activity tracking device (such as a FitBit® device, a Misfit® device, and/or a Sony Smartband® device), a smart watch, smart clothing (e.g., OMsignal® smartwear, etc.), and/or smart glasses (such as Google Glass® eyewear). In addition, the system controller 110 may be configured to communicate via the network with one or more other control systems (e.g., a building management system, a security system, etc.).

The mobile device 190 may be configured to transmit digital messages to the system controller 110, for example, in one or more Internet Protocol packets. For example, the mobile device 190 may be configured to transmit digital messages to the system controller 110 over the LAN and/or via the internet. The mobile device 190 may be configured to transmit digital messages over the internet to an external service (e.g., If This Then That (IFTTT®) service), and then the digital messages may be received by the system controller 110. The mobile device 190 may transmit and receive RF signals 109 via a Wi-Fi communication link, a Wi-MAX communications link, a Bluetooth communications link, a near field communication (NFC) link, a cellular communications link, a television white space (TVWS) communication link, or any combination thereof. Alternatively or additionally, the mobile device 190 may be configured to transmit RF signals according to the proprietary protocol. The load control system 100 may comprise other types of network devices coupled to the network, such as a desktop personal computer, a Wi-Fi or wireless-communication-capable television, or any other suitable Internet-Protocol-enabled device. Examples of load control systems operable to communicate with mobile and/or network devices on a network are described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2013/0030589, published Jan. 31, 2013, entitled LOAD CONTROL DEVICE HAVING INTERNET CONNECTIVITY, the entire disclosure of which is hereby incorporated by reference.

The system controller 110 may be configured to determine the location of the mobile device 190 and/or the occupant 192. The system controller 110 may be configured to control (e.g., automatically control) the load control devices (e.g., the dimmer switch 120, the LED driver 130, the plug-in load control device 140, the motorized window treatments 150, and/or the temperature control device 160) in response to determining the location of the mobile device 190 and/or the occupant 192. One or more of the control devices of the load control system 100 may transmit beacon signals, for example, RF beacon signals transmitted using a short-range and/or low-power RF technology, such as Bluetooth technology. The load control system 100 may also comprise at least one beacon transmitting device 194 for transmitting the beacon signals. The mobile device 190 may be configured to receive a beacon signal when located near a control device that is presently transmitting the beacon signal. A beacon signal may comprise a unique identifier identifying the location of the load control device that transmitted the beacon signal. Since the beacon signal may be transmitted using a short-range and/or low-power technology, the unique identifier may indicate the approximate location of the mobile device 190. The mobile device 190 may be configured to transmit the unique identifier to the system controller 110, which may be configured to determine the location of the mobile device 190 using the unique identifier (e.g., using data stored in memory or retrieved via the Internet). An example of a load control system for controlling one or more electrical loads in response to the position of a mobile device and/or occupant inside of a building is described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2016/0056629, published Feb. 25, 2016, entitled LOAD CONTROL SYSTEM RESPONSIVE TO LOCATION OF AN OCCUPANT AND MOBILE DEVICES, the entire disclosure of which is hereby incorporated by reference.

The visible light sensors 180, 182 may each comprise, for example, a camera and a fish-eye lens. The camera of the first visible light sensor 180 may be directed into the room 102 and may be configured to record images of the room 102. For example, the first visible light sensor 180 may be mounted to a ceiling of the room 102 (as shown in FIG. 1), and/or may be mounted to a wall of the room. If the first visible light sensor 180 is mounted to the ceiling, the images recorded by the camera may be top down views of the room 102. The camera of the second visible light sensor 182 may be directed outside of the room 102 (e.g., out of the window 104) and may be configured to record images from outside of the building. For example, the second visible light sensor 182 may be mounted to one of the windows 104 (as shown in FIG. 1), and/or may be mounted to the exterior of the building.

The visible light sensors 180, 182 may each be configured to process images recorded by the camera and transmit one or more messages (e.g., digital messages) to the load control devices in response to the processed images. Each visible light sensor 180, 182 may be configured to sense one or more environmental characteristics of a space (e.g., the room 102 and/or the room 200) from the images. For example, the first visible light sensor 180 may be configured to operate in one or more sensor modes (e.g., an occupancy and/or vacancy sensor mode, a daylight sensor mode, a color sensor mode, a glare detection sensor mode, an occupant count mode, etc.) In addition, the second visible light sensor 182 may be configured to operate in one or more same or different sensor modes (e.g., a color sensor mode, a glare detection sensor mode, a weather sensor mode, etc.) Each visible light sensor 180, 182 may execute different algorithms to process the images in each of the sensor modes to determine data to transmit to the load control devices. The visible light sensors 180, 182 may each transmit digital messages via the RF signals 108 (e.g., using the proprietary protocol) in response to the images. The visible light sensors 180, 182 may each send the digital messages directly to the load control devices and/or to the system controller 110, which may then communicate the messages to the load control devices. Each visible light sensor 180, 182 may comprise a first communication circuit for transmitting and receiving the RF signals 108 using the proprietary protocol.

The visible light sensors 180, 182 may each be configured to perform a plurality of sensor events to sense various environmental characteristics of the interior and/or the exterior of the room 102. For example, to perform a sensor event, each visible light sensor 180, 182 may be configured to operate in one of a plurality of sensor modes to execute one or more corresponding algorithms to sense the environmental characteristic. In addition, each visible light sensor 180, 182 may configured to obtain from memory certain pre-configured operational characteristics (e.g., sensitivity, baseline values, threshold values, limit values, etc.) that may be used by the algorithm to sense the environmental characteristic during the sensor event.

Further, each visible light sensor 180, 182 may be configured to focus on one or more regions of interest in the image recorded by the camera when processing the image to sense the environmental characteristic during the sensor event. For example, certain areas of the image recorded by the camera of one of the visible light sensors 180, 182 may be masked (e.g., digitally masked), such that the respective visible light sensor may not process the portions of the image in the masked areas. Each visible light sensor 180, 182 may be configured to apply a mask (e.g., a predetermined digital mask that may be stored in memory) to focus on a specific region of interest, and process the portion of the image in the region of interest. In addition, each visible light sensor 180, 182 may be configured to focus on multiple regions of interest in the image at the same time. Specific mask(s) may be defined for each sensor event.

The visible light sensors 180, 182 may each be configured to dynamically change between the sensor modes, apply digital masks to the images, and/or adjust operational characteristics depending upon the present sensor event. Each visible light sensor 180, 182 may be configured to perform a number of different sensor events to sense a plurality of the environmental characteristics of the space. For example, each visible light sensor 180, 182 may be configured to sequentially and/or periodically step through the sensor events to sense the plurality of the environmental characteristics of the space. Each sensor event may be characterized by a sensor mode (e.g., specifying an algorithm to use), one or more operational characteristics, and/or one or more digital masks. An example of a visible light sensor having multiple sensor modes is described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2017/0171941, published Jun. 15, 2017, entitled LOAD CONTROL SYSTEM HAVING A VISIBLE LIGHT SENSOR, the entire disclosure of which is hereby incorporated by reference.

The first visible light sensor 180 may be configured to operate in the occupancy and/or vacancy sensor mode to determine an occupancy and/or vacancy condition in the room 102 in response to detection of movement within one or more regions of interest. The first visible light sensor 180 may be configured to use an occupancy and/or vacancy detection algorithm to determine that the room 102 is occupied in response to the amount of movement and/or the velocity of movement exceeding an occupancy threshold.

During a sensor event for detecting occupancy and/or vacancy, the first visible light sensor 180 may be configured to apply a predetermined mask to focus on one or more regions of interest in one or more images recorded by the camera and determine occupancy or vacancy of the space based on detecting or not detecting motion in the regions of interest. The first visible light sensor 180 may be responsive to movement in the regions of interest and not be responsive to movement in the masked-out areas. For example, the first visible light sensor 180 may be configured to apply a mask to an image of the room to exclude detection of motion in the doorway 108 and/or the windows 104 of the room 102, and may focus on a region of interest that includes the interior space of the room. The first visible light sensor 180 may be configured to apply a first mask to focus on a first region of interest, apply a second mask to focus on a second region of interest, and determine occupancy or vacancy based on movement detected in either of the regions of interest. In addition, the first visible light sensor 180 may be configured to focus on multiple regions of interest in the image at the same time by applying different masks to the image(s).

The first visible light sensor 180 may be configured to adjust certain operational characteristics (e.g., sensitivity) to be used by the occupancy and/or vacancy algorithm depending upon the present sensor event. The occupancy threshold may be dependent upon the sensitivity. For example, the first visible light sensor 180 may be configured to be more sensitive or less sensitive to movements in a first region of interest than in a second region of interest. For example, the first visible light sensor 180 may be configured to increase the sensitivity and apply a mask to focus on a region of interest around a keyboard of a computer to be more sensitive to movements around the keyboard. In other words, by using masks that focus on “smaller” vs “larger” (e.g., the keyboard vs. the desk surface on which the keyboard may sit), the first visible light sensor 180 may be configured to increase and/or decrease the sensitivity of detected or not detected movements. In addition, through the use of masks, the first visible light sensor 180 may be configured to not simply detect movement in the space, but detect where that movement occurred.

The first visible light sensor 180 may transmit digital messages to the system controller 110 via the RF signals 108 (e.g., using the proprietary protocol) in response to detecting the occupancy or vacancy conditions. The system controller 110 may be configured to turn the lighting loads (e.g., lighting load 122 and/or the LED light source 132) on and off in response to receiving an occupied command and a vacant command, respectively. Alternatively, the first visible light sensor 180 may transmit digital messages directly to the lighting loads. The first visible light sensor 180 may operate as a vacancy sensor, such that the lighting loads are only turned off in response to detecting a vacancy condition (e.g., and not turned on in response to detecting an occupancy condition). Examples of RF load control systems having occupancy and vacancy sensors are described in greater detail in commonly-assigned U.S. Pat. No. 8,009,042, issued Aug. 30, 2011 Sep. 3, 2008, entitled RADIO-FREQUENCY LIGHTING CONTROL SYSTEM WITH OCCUPANCY SENSING; U.S. Pat. No. 8,199,010, issued Jun. 12, 2012, entitled METHOD AND APPARATUS FOR CONFIGURING A WIRELESS SENSOR; and U.S. Pat. No. 8,228,184, issued Jul. 24, 2012, entitled BATTERY-POWERED OCCUPANCY SENSOR, the entire disclosures of which are hereby incorporated by reference.

The first visible light sensor 180 may also be configured to operate in the daylight sensor mode to measure a light intensity at a location of the space. For example, the first visible light sensor 180 may apply a digital mask to focus on only a specific location in the space (e.g., on a task surface, such as a table 106 as shown in FIG. 1) and may use a daylighting algorithm to measure the light intensity at the location. For example, the first visible light sensor 180 may be configured to apply a mask to focus on a region of interest that includes the surface of a desk. The first visible light sensor 180 may be configured to integrate light intensities values of the pixels of the image across the region of interest to determine a measured light intensity at the surface of the desk.

The first visible light sensor 180 may transmit digital messages (e.g., including the measured light intensity) to the system controller 110 via the RF signals 108 for controlling the intensities of the lighting load 122 and/or the LED light source 132 in response to the measured light intensity. The first visible light sensor 180 may be configured to focus on multiple regions of interest in the image recorded by the camera and measure the light intensity in each of the different regions of interest. Alternatively, the first visible light sensor 180 may transmit digital messages directly to the lighting loads. The first visible light sensor 180 may be configured to adjust certain operational characteristics (e.g., gain) based on the region of interest in which the light intensity is presently being measured. Examples of RF load control systems having daylight sensors are described in greater detail in commonly-assigned U.S. Pat. No. 8,410,706, issued Apr. 2, 2013, entitled METHOD OF CALIBRATING A DAYLIGHT SENSOR; and U.S. Pat. No. 8,451,116, issued May 28, 2013, entitled WIRELESS BATTERY-POWERED DAYLIGHT SENSOR, the entire disclosures of which are hereby incorporated by reference.

The system controller 110 may be configured to determine a degradation in the light output of one or more of the lighting loads (e.g., the lighting load 122 and/or the LED light source 132) in the space, and to control the intensities of the lighting loads to compensate for the degradation (e.g., lumen maintenance). For example, the system controller 110 may be configured to individually turn on each lighting load (e.g., when it is dark at night) and measure the magnitude of the light intensity at a location (e.g., on the table 106 or the desk 220). For example, the system controller 110 may be configured to turn on the lighting load 122 at night and control the first visible light sensor 180 to record an image of the room, to apply a mask to focus on a region of interest that the lighting load 122 illuminates (e.g., the surface of table 106 or the desk 220), to measure the light intensity in that region of interest, and to communicate that value to the system controller 110. The system controller 110 may store this value as a baseline value. At a time and/or date thereafter, the system controller 110 may repeat the measurement and compare the measurement to the baseline value. If the system controller 110 determines there to be a degradation, it may control the lighting load 122 to compensate for the degradation, alert maintenance, etc.

The first visible light sensor 180 may also be configured to operate in the color sensor mode to sense a color (e.g., measure a color temperature) of the light emitted by one or more of the lighting loads in the space (e.g., to operate as a color sensor and/or a color temperature sensor). For example, the first visible light sensor 180 may be configured to apply a mask to focus on a region of interest in the room 102 and may use a color sensing algorithm to determine a measured color and/or color temperature in the room. For example, the first visible light sensor 180 may integrate color values of the pixels of the image across the region of interest to determine the measured color and/or color temperature in the room. The first visible light sensor 180 may transmit digital messages (e.g., including the measured color temperature) to the system controller 110 via the RF signals 108 for controlling the color (e.g., the color temperatures) of the lighting load 122 and/or the LED light source 132 in response to the measured light intensity (e.g., color tuning of the light in the space). Alternatively, the first visible light sensor 180 may transmit digital messages directly to the lighting loads. An example of a load control system for controlling the color temperatures of one or more lighting loads is described in greater detail in commonly-assigned U.S. Pat. No. 9,538,603, issued Jan. 3, 2017, entitled SYSTEMS AND METHODS FOR CONTROLLING COLOR TEMPERATURE, the entire disclosure of which is hereby incorporated by reference.

The first visible light sensor 180 may be configured to operate in a glare detection sensor mode. For example, the first visible light sensor 180 may be configured execute a glare detection algorithm to determine a depth of direct sunlight penetration into the space from the image recorded by the camera. For example, the first visible light sensor 180 may be configured to apply a mask to focus on a region of interest on the floor of the room 102 near the windows 104 to sense the depth of direct sunlight penetration into the room. Based on a detection and/or measurement of the depth of direct sunlight penetration into the room, the first visible light sensor 180 may transmit digital messages to the system controller 110 via the RF signals 108 to limit the depth of direct sunlight penetration into the space, for example, to prevent direct sunlight from shining on a surface (e.g., a table or a desk). The system controller 110 may be configured to lower the window treatment fabric 152 of each of the motorized window treatments 150 to prevent the depth of direct sunlight penetration from exceeded a maximum sunlight penetration depth. Alternatively, the first visible light sensor 180 may be configured to directly control the window treatments 150 to lower of the window treatment fabric 152. Examples of methods for limiting the sunlight penetration depth in a space are described in greater detail in previously-referenced U.S. Pat. No. 8,288,981.

The first visible light sensor 180 may be configured to focus only on daylight entering the space through, for example, one or both of the windows 104 (e.g., to operate as a window sensor). The system controller 110 may be configured to control the lighting loads (e.g., the lighting load 122 and/or the LED light source 132) in response to the magnitude of the daylight entering the space. The system controller 110 may be configured to override automatic control of the motorized window treatments 150, for example, in response to determining that it is a cloudy day or an extremely sunny day. Alternatively, the first visible light sensor 180 may be configured to directly control the window treatments 150 to lower of the window treatment fabric 152. Examples of load control systems having window sensors are described in greater detail in commonly-assigned U.S. Patent Application Publication No. 2014/0156079, published Jun. 5, 2014, entitled METHOD OF CONTROLLING A MOTORIZED WINDOW TREATMENT, the entire disclosure of which is hereby incorporated by reference.

The first visible light sensor 180 may be configured to detect a glare source (e.g., sunlight reflecting off of a surface) outside or inside the room 102 in response to the image recorded by the camera. The system controller 110 may be configured to lower the window treatment fabric 152 of each of the motorized window treatments 150 to eliminate the glare source. Alternatively, the first visible light sensor 180 may be configured to directly control the window treatments 150 to lower of the window treatment fabric 152 to eliminate the glare source.

The first visible light sensor 180 may also be configured to operate in the occupant count mode and may execute an occupant count algorithm to count the number of occupants a particular region of interest, and/or the number of occupants entering and/or exiting the region of interest. For example, the system controller 110 may be configured to control the HVAC system 162 in response to the number of occupants in the space. The system controller 110 may be configured to control one or more of the load control devices of the load control system 100 in response to the number of occupants in the space exceeding an occupancy number threshold. Alternatively, the first visible light sensor 180 may be configured to directly control the HVAC system 162 and other load control devices.

The second visible light sensor 182 may be configured to operate in a glare detection sensor mode. For example, the second visible light sensor 182 may be configured execute a glare detection algorithm to determine if a glare condition may exist in the room 102 from one or more images recorded by the camera. The glare condition in the room 102 may be generated by a glare source outside of the room, such as the sun, an external lamp (e.g., an outdoor building light or a streetlight), and/or a reflection of the sun or other bright light source. The second visible light sensor 182 may be configured to analyze one or more images recorded by the camera to determine if an absolute glare condition exists and/or a relative glare condition exists outside of the room 102 as viewed from one of the windows 104. An absolute glare condition may occur when the light level (e.g., the light intensity) of a potential glare source is too high (e.g., exceeds an absolute glare threshold). A relative glare condition (e.g., a contrast glare condition) may occur when the difference between the light level of a potential glare source and a background light level (e.g., a baseline) is too high (e.g., exceeds a relative glare threshold).

Based on a detection of a glare condition, the second visible light sensor 182 may transmit digital messages to the system controller 110 via the RF signals 108 to open, close, or adjust the position of the window treatment fabric 152 of each of the motorized window treatments 150. For example, the system controller 110 may be configured to lower the window treatment fabric 152 of each of the motorized window treatments 150 to prevent direct sunlight penetration onto a task surface in the room 102 (e.g., a desk or a table). If the second visible light sensor 182 does not detect a glare condition, the system controller 110 may be configured to open the motorized window treatments 150 (e.g., to control the position of the window treatment fabric 152 to a fully-open position or a visor position). Alternatively, the second visible light sensor 182 may be configured to directly control the window treatments 150.

The operation of the load control system 100 may be programmed and configured using, for example, the mobile device 190 or other network device (e.g., when the mobile device is a personal computing device). The mobile device 190 may execute a graphical user interface (GUI) configuration software for allowing a user to program how the load control system 100 will operate. For example, the configuration software may run as a PC application or a web interface. The configuration software and/or the system controller 110 (e.g., via instructions from the configuration software) may generate a load control database that defines the operation of the load control system 100. For example, the load control database may include information regarding the operational settings of different load control devices of the load control system (e.g., the dimmer switch 120, the LED driver 130, the plug-in load control device 140, the motorized window treatments 150, and/or the thermostat 160). The load control database may comprise information regarding associations between the load control devices and the input devices (e.g., the remote control device 170, the visible light sensor 180, etc.). The load control database may comprise information regarding how the load control devices respond to inputs received from the input devices. Examples of configuration procedures for load control systems are described in greater detail in commonly-assigned U.S. Pat. No. 7,391,297, issued Jun. 24, 2008, entitled HANDHELD PROGRAMMER FOR A LIGHTING CONTROL SYSTEM; U.S. Patent Application Publication No. 2008/0092075, published Apr. 17, 2008, entitled METHOD OF BUILDING A DATABASE OF A LIGHTING CONTROL SYSTEM; and U.S. Patent Application Publication No. 2014/0265568, published Sep. 18, 2014, entitled COMMISSIONING LOAD CONTROL SYSTEMS, the entire disclosure of which is hereby incorporated by reference.

The operation of the visible light sensors 180, 182 may be programmed and configured using the mobile device 190 or other network device. Each visible light sensor 180, 182 may comprise a second communication circuit for transmitting and receiving the RF signals 109 (e.g., directly with the network device 190 using a standard protocol, such as Wi-Fi or Bluetooth). During the configuration procedure of the load control system 100, the visible light sensors 180, 182 may each be configured to record an image of the space and transmit the image to the network device 190 (e.g., directly to the network device via the RF signals 109 using the standard protocol). The network device 190 may display the image on the visual display and a user may configure the operation of each visible light sensor 180, 182 to set one or more configuration parameters (e.g., configuration information) of the visible light sensor. For example, for different environmental characteristics to be sensed and controlled by the visible light sensors 180, 182 (e.g., occupant movements, light level inside of the room, daylight level outside of the room), the user may indicate different regions of interest on the image by tracing (such as with a finger or stylus) masked areas on the image displayed on the visual display. The visible light sensors 180, 182 may each be configured to establish different masks and/or operational characteristics depending upon the environmental characteristic to be sensed (e.g., occupant movements, light level inside of the room, daylight level outside of the room, color temperature, etc.).

After configuration of the visible light sensors 180, 182 is completed at the network device 190, the network device may transmit configuration information to the visible light sensors (e.g., directly to the visible light sensors via the RF signals 109 using the standard protocol). The visible light sensors 180, 182 may each store the configuration information in memory, such that the visible light sensors may operate appropriately during normal operation. For example, for each sensor event the visible light sensors 180, 182 are to monitor, the network device 190 may transmit to the respective visible light sensor the sensor mode for the event, one or more masks defining regions of interest for the event, possibly an indication of the algorithm to be used to sense the environmental characteristic of the event, and one or more operational characteristics for the event.

While the load control system 100 of FIG. 1 has been described above with reference to two visible light sensors 180, 182, the load control system 100 could also simply include either one of the visible light sensors 180, 182. For example, the load control system 100 may not include the first visible light sensor 180 and may only include the second visible light sensor 182, which may be mounted to the window 104 and may operate to prevent sun glare from occurring on a task surface in the room 102. In addition, the load control system 100 may have more than two visible light sensors. Each window may have a respective visible light sensor, or a visible light sensor may receive an image through a window that is representative of a group of windows having motorized window treatments that are collectively controlled based on the image of a single visible light sensor.

FIG. 2 is a simplified side view of an example space 200 having a visible light sensor 210 (e.g., such as the second visible light sensor 182 of the load control system 100 shown in FIG. 1). The visible light sensor 210 may be mounted to a window 202, which may be located in a façade 204 of a building in which the space 200 is located and may allow light (e.g., sunlight) to enter the space. The visible light sensor 210 may be mounted to an inside surface of the window 202 (e.g., as shown in FIG. 2) or an outside surface of the window 202. The window 202 may be characterized by a height h_(WIN-BOT) of the bottom of the window and a height h_(WIN-TOP) of the top of the window. The space 200 may also comprise a work surface, e.g., a table 206, which may have a height h_(WORK) and may be located at a distance d_(WORK) from the window 202.

A motorized window treatment, such as a motorized roller shade 220 may be mounted over the window 202. The motorized roller shade 220 may comprise a roller tube 222 around which a shade fabric 224 may be wrapped. The shade fabric 224 may have a hembar 226 at the lower edge of the shade fabric that may be a height h_(HEMBAR) above the floor. The motorized roller shade 220 may comprise a motor drive unit (not shown) that may be configured to rotate the roller tube 222 to move the shade fabric 224 between a fully-open position P_(OPEN) (e.g., at which the window 202 is not covered and the hembar 226 may be at the top of the window) and a fully-closed position P_(CLOSED) (e.g., at which the window 202 is fully covered and the hembar 226 may be at the bottom of the window). Further, the motor drive unit may control the position of the shade fabric 222 to one of a plurality of preset positions between the fully-open position and the fully-closed position.

A glare condition for an occupant of the room 200 may be caused by a glare source, such as the sun, an external lamp (e.g., an outdoor building light or a streetlight), or a reflection of the sun or other bright light source, that may be located outside of the window 202. For example, light from the glare source may shine through the window 202 into the room 200 and may extend into the room (e.g., onto the floor) for a penetration distance d_(PEN) from the window 202 and/or from the façade 204. The penetration distance d_(PEN) of the light may be measured in a direction normal to the window 202 and/or from the façade 204. The penetration distance d_(PEN) of the light from the glare source may be a function of the height h_(HEMBAR) of the hembar 226 of the motorized roller shade 220 and a profile angle θ_(P) of the glare source. The profile angle θ_(P) may represent the position of the glare source outside of the window 202. The position of the glare source may be defined by an altitude angle (e.g., a vertical angle) and an azimuth angle (e.g., a horizontal angle) from the center of view of the visible light sensor 210 (e.g., a direction perpendicular to the window 202 and/or the façade 204. The profile angle θ_(P) may be defined as an angle of a projection of the line from the glare source to the visible light sensor onto a vertical plane that is perpendicular to the window 202 and/or the façade 204. The penetration distance d_(PEN) of light from the glare source onto the floor of the space 200 (e.g., in the direction normal to the window 202 and/or the façade 204) may be determined by considering a triangle formed by the penetration distance d_(PEN), the height h_(HEMBAR) of the hembar 226, and a length l of the light shining into the space 200 in the normal direction to the window 202, as shown in the side view of the window 202 in FIG. 2, e.g.,

tan(θ_(P))=h _(HEMBAR) /d _(PEN).   (Equation 1)

In response to the visible light sensor 210 detecting a glare source outside of the window 202, the visible light sensor 210 and/or a system controller (e.g., the system controller 110) may be configured to determine a position to which to control the shade fabric 224 (e.g., the hembar 226 of the shade fabric 224) of the motorized roller shade 220 to prevent a glare condition in the space. For example, the position of the hembar 226 of the motorized roller shade 220 may be adjusted to prevent the penetration distance d_(PEN) from exceeding a maximum penetration distance d_(PEN-MAX). For example, if the sun is shining in the window 220, the visible light sensor 210 may be configured to process the image to determine the profile angle θ_(S) that defines the location of the glare source. The visible light sensor 210 and/or the system controller may be configured to calculate the desired height h_(HEMBAR) above the floor to which to control the hembar 226 to prevent the light from the glare source from exceeding the maximum penetration distance d_(PEN-MAX), e.g.,

h _(HEMBAR)=tan(θ_(P))·d _(PEN-MAX).   (Equation 2)

The visible light sensor 210 and/or the system controller may be configured with values for the top and bottom heights h_(WIN-TOP), h_(WIN-BOT) of the window 220, e.g., during configuration of the visible light sensor and/or the system controller. The visible light sensor 210 and/or the system controller may be configured to determine a desired position of the hembar 226 between the fully-open position P_(OPEN) and the fully-closed position P_(CLOSED) of the motorized roller shade 220 using the top and bottom heights h_(WIN-TOP), h_(WIN-BOT) and the calculated height h_(HEMBAR) of the hembar.

In addition, the position of the hembar 226 of the motorized roller shade 220 may be adjusted to prevent light from the glare source from shining on the table 206. For example, the visible light sensor 210 and/or the system controller may be configured to calculate the desired height h_(HEMBAR) above the floor to which to control the hembar 226 to prevent the light from the glare source from shining on the table 206, e.g.,

h _(HEMBAR)=(tan(θ_(P))·d _(WORK))+h _(WORK).   (Equation 3)

The position of the hembar 226 of the motorized roller shade 220 may be adjusted to prevent light from the glare source from shining on in the eyes of occupants of the space 200. For example, the visible light sensor 210 and/or the system controller may be configured to calculate the desired height h_(HEMBAR) above the floor to which to control the hembar 226 based on an estimated height of the occupant's eyes and/or an estimated distance of the occupants from the window. For example, if the room 200 includes a visible light sensor located within the room (e.g., as the visible light sensor 180 of the load control system 100 of FIG. 1), that visible light sensor may be configured to process an image of the room to determine the values for the height of the occupant's eyes and/or the distance of the occupants from the window.

The visible light sensor 210 and/or the system controller may store values for the maximum penetration distance d_(PEN-MAX), the height h_(WORK) of the table 206, and the distance d_(WORK) of the table 206 from the window 202. For example, the visible light sensor 210 and/or the system controller may be configured with these values during the configuration of the visible light sensor 210 and/or the system controller (e.g., using the mobile device 190 or other network device). Additionally or alternatively, the visible light sensor 206 and/or the system controller may be configured with default values for the maximum penetration distance d_(PEN-MAX), the height h_(WORK) of the table 206, and the distance d_(WORK) of the table 206 from the window 202. For example, if the room 200 includes a visible light sensor located within the room (e.g., as the visible light sensor 180 of the load control system 100 of FIG. 1), that visible light sensor may be configured to process an image of the room to determine the values for the maximum penetration distance d_(PEN-MAX), the height h_(WORK) of the table 206, and the distance d_(WORK) of the table 206 from the window 202, and transmit those values to the visible light sensor 210 on the window 202 and/or the system controller.

FIG. 3 is a simplified block diagram of an example visible light sensor 300, which may be deployed as one or both of the visible light sensors 180, 182 of the load control system 100 shown in FIG. 1 and/or the visible light sensor 210 of FIG. 2. The visible light sensor 300 may comprise a control circuit 310, for example, a microprocessor, a programmable logic device (PLD), a microcontroller, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or any suitable processing device. The control circuit 310 may be coupled to a memory 312 for storage of sensor events, masks, operational characteristics, etc. of the visible light sensor 300. The memory 312 may be implemented as an external integrated circuit (IC) or as an internal circuit of the control circuit 310.

The visible light sensor 300 may comprise a visible light sensing circuit 320 having an image recording circuit, such as a camera 322, and an image processing circuit, such as a processor 324. The image processor 324 may comprise a digital signal processor (DSP), a microprocessor, a programmable logic device (PLD), a microcontroller, an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or any suitable processing device. The camera 322 may be positioned towards a space in which one or more environmental characteristics are to be sensed in a space (e.g., into the room 102). The camera 322 may be configured to capture or record an image. For example, the camera 322 may be configured to capture images at a particular sampling rate, where a single image may be referred to as a frame acquisition. One example frame acquisition rate is approximately ten frames per second. The frame acquisition rate may be limited to reduce the required processing power of the visible light sensor. Each image may consist of an array of pixels, where each pixel has one or more values associated with it. A raw RGB image may have three values for each pixel: one value for each of the red, green, and blue intensities, respectively. One implementation may use the existing RGB system for pixel colors, where each component of the intensity has a value from 0-255. For example, a red pixel would have an RGB value of (255, 0, 0), whereas a blue pixel would have an RGB value of (0, 0, 255). Any given pixel that is detected to be a combination of red, green, and/or blue may be some combination of (0-255, 0-255, 0-255). One will recognize that over representations for an image may be used.

The camera 322 may provide the captured image (e.g., a raw image) to the image processor 324. The image processor 324 may be configured to process the image and provide to the control circuit 310 one or more sense signals that are representative of the sensed environmental characteristics (e.g., an occurrence of movement, an amount of movement, a direction of movement, a velocity of movement, a counted number of occupants, a light intensity, a light color, an amount of direct sunlight penetration, etc.). For example, the one or more sense signals provided to the control circuit 310 may be representative of movement in the space and/or a measured light level in the space.

In addition, the image processor 324 may provide a raw image or a processed (e.g., preprocessed) image to the control circuit 310, which may be configured to process the image to determine sensed environmental characteristics. Regardless, the control circuit 310 may then use the sensed environmental characteristics to transmit control commands to load devices (e.g., directly or through system controller 110).

One example of a processed image, as is known in the art, is the luminance of a pixel, which may be measured from the image RGB by adding R, G, B intensity values, weighted according to the following formula:

Luminance (perceived)=(0.299*R+0.587*G+0.114*B).   (Equation 4)

The example weighting coefficients may factor in the non-uniform response of the human eye to different wavelengths of light. However, other coefficients may alternatively be used.

As previously mentioned, if the visible light sensor 300 have a fish-eye lens, the image captured by the camera 322 may be warped. The image processor 324 may be configured to preprocess the image to de-warp the image and to generate a non-warped image.

Another image processing technique may include mapping the RGB sensor response to CIE tristimulus values to acquire chromaticity coordinates and thereby the Correlated Color Temperature (CCT). An example method is described by Joe Smith in the following reference: Calculating Color Temperature and Illuminance using the TAOS TCS3414CS Digital Color Sensor, Intelligent Opto Sensor Designer's Notebook, Feb. 27, 2009. Another example of a processed image may be an image to which a digital filter, or a digital mask has been applied. A digital mask may be used to eliminate regions within the image, which may not have value for further analysis and processing. Alternatively, a complement of a digital mask may be a region of interest (e.g., an area within an image that has been identified for further processing or analysis). A processed image may also be created via a technique known as background subtraction. For example, using background subtraction, a background image, which may incorporate the history of the image over time (e.g., the previous state of the room), may be subtracted from the current image (e.g., the current state of the room). This technique may identify differences in the images. Background subtraction may be useful for detecting movement in an image and for occupancy and vacancy detection. Various algorithms may be used for background maintenance, to determine how to effectively combine pixels over time into the background image. Some example background maintenance algorithms may include: adjusted frame difference, mean and threshold, mean and covariance, mixture of Gaussians, and normalized block correlation. These and other similar details inherent to image processing would be familiar to one skilled in the art.

The control circuit 310 and/or the image processor 324 may be configured to apply one or more masks to focus on one or more regions of interest in the image (e.g., the raw image and/or the preprocessed image) to sense one or more environmental characteristics of the space. As used herein, a mask may be any definition to define a region of interest of an image. For example, assuming an image may be defined as an N×M array of pixels where each pixel has a defined coordinate/position in the array, a mask be defined as a sequence of pixel coordinates that define the outer perimeter of a region of interest within the image. As another example, a mask may be defined as an N×M array that corresponds to the N×M array of pixels of an image. Each entry of the mask may be a 1 or 0, for example, whereby entries having a 1 may define the region of interest. Such a representation may allow an image array and a mask array to be “ANDED,” which may cancel or zero out all pixels of the image that are not of interest. As another alternative, rather than a mask defining the region of interest of the image, a mask may define the region that is not of interest. These are merely examples and other representations may be used.

The visible light sensor 300 may comprise a first communication circuit 330 configured to transmit and receive digital messages via a first communication link using a first protocol. For example, the first communication link may comprise a wireless communication link and the first communication circuit 330 may comprise an RF transceiver coupled to an antenna. In addition, the first communication link may comprise a wired digital communication link and the first communication circuit 330 may comprise a wired communication circuit. The first protocol may comprise a proprietary protocol, such as, for example, the ClearConnect protocol. The control circuit 310 may be configured to transmit and receive digital messages via the first communication link during normal operation of the visible light sensor 300. The control circuit 310 may be configured to transmit an indication of the sensed environmental characteristic via the first communication link during normal operation of the visible light sensor 300. For example, the control circuit 310 may be configured to transmit an indication of a detected state (e.g., an occupancy or vacancy condition) and/or a measured environmental characteristic (e.g., a measured light level) via the first communication link during normal operation of the visible light sensor 300.

The visible light sensor 300 may comprise a second communication circuit 332 configured to transmit and receive digital messages via a second communication link using a second protocol. For example, the second communication link may comprise a wireless communication link and the second communication circuit 332 may comprise an RF transceiver coupled to an antenna. In addition, the second communication link may comprise a wired digital communication link and the second communication circuit 332 may comprise a wired communication circuit. The second protocol may comprise a standard protocol, such as, for example, the Wi-Fi protocol, the Bluetooth protocol, the Zigbee protocol, etc. The control circuit 310 may be configured to transmit and receive digital messages via the second communication link during configuration of the visible light sensor 300. For example, the control circuit 310 may be configured to transmit an image recorded by the camera 322 via the second communication link during configuration of the visible light sensor 300.

The visible light sensor 300 may comprise a power source 340 for producing a DC supply voltage V_(CC) for powering the control circuit 310, the memory 312, the image processor 324, the first and second communication circuits 330, 332, and other low-voltage circuitry of the visible light sensor 300. The power source 340 may comprise a power supply configured to receive an external supply voltage from an external power source (e.g., an AC mains line voltage power source and/or an external DC power supply). In addition, the power source 340 may comprise a battery for powering the circuitry of the visible light sensor 300.

The visible light sensor 300 may further comprise a low-power occupancy sensing circuit, such as a passive infrared (PIR) detector circuit 350. The PIR detector circuit 350 may generate a PIR detect signal V_(PIR) (e.g., a low-power occupancy signal) that is representative of an occupancy and/or vacancy condition in the space in response to detected passive infrared energy in the space. The PIR detector circuit 350 may consume less power than the visible light sensing circuit 320. However, the visible light sensing circuit 320 may be more accurate than the PIR detector circuit 350. For example, when the power source 340 is a battery, the control circuit 310 may be configured to disable the visible light sensing circuit 320 and use the PIR detector circuit 350 to detect occupancy conditions. The control circuit 310 may disable the light sensing circuit 320, for example, when the space is vacant. The control circuit 310 may detect an occupancy condition in the space in response to the PIR detect signal V_(PIR) and may subsequently enable the visible light sensing circuit 320 to detect a continued occupancy condition and/or a vacancy condition. The control circuit 310 may enable the visible light sensing circuit 320 immediately after detecting an occupancy condition in the space in response to the PIR detect signal V_(PIR). The control circuit 310 may also keep the visible light sensing circuit 320 disabled after detecting an occupancy condition in the space (in response to the PIR detect signal V_(PIR)). The control circuit 310 may keep the visible light sensing circuit 320 disabled until the PIR detect signal V_(PIR) indicates that the space is vacant. The control circuit 310 may not make a determination that the space is vacant until the visible light sensing circuit 320 subsequently indicates that the space is vacant.

When the visible light sensor 300 is mounted to a window (e.g., as the second visible light sensor 182 of the load control system of FIG. 1), the control circuit 310 may be configured to record one or more images of the space outside of the window via the camera 322 and process the one or more images to determine if a glare condition exists. The visible light sensor 300 may comprise a fish-eye lens (not shown), which may cause the images recorded by the camera 322 to be warped. The control circuit 310 and/or the image processor 324 may be configured to de-warp the images recorded by the camera 322 to produce non-warped images, which may be characterized by rows of constant profile angle.

The control circuit 310 may be configured to process each pixel of the non-warped images to determine if a glare conditions exists for each pixel. The control circuit 310 may begin processing the image at a portion of the image which may be relative to a position on a window or group of windows from which the image is taken. For example, the portion of the image may represent a bottom portion of the window and the control circuit may begin processing the non-warped image at the bottom portion. The bottom portion may include a predefined number of pixel rows from the bottom of the image (e.g., a bottom row of pixels in the non-warped image). The control circuit may also, or alternatively, begin processing the image from a top portion (e.g., a top row of pixels) of the image. The portion of the image that is processed first may depend on the direction from which the motorized window treatment moves the covering material to close the covering material and/or the current position of the covering material to reduce the processing resources utilized to identify a glare condition in the image.

The control circuit 310 may be configured to start at the bottom row of pixels of the non-warped image (e.g., at the left or right side). The control circuit 310 may step through each pixel in the bottom row and process each pixel to determine if a glare condition exists before moving up to the next row. After the control circuit 310 determines that a glare condition exists, the control circuit 310 may stop processing the non-warped image and may operate to control one or more motorized window treatments (e.g., such as the motorized window treatments 140 of FIG. 1 and/or the motorized roller shade 220 of FIG. 2) to remove the glare condition (e.g., as will be described in greater detail below). This may prevent the rest of the image from being processed to detect the glare condition. If the control circuit 310 processes the entire image without detecting a glare condition, the control circuit may conclude that no glare conditions exist and may control the motorized window treatment to open. Since the control circuit 310 processes the pixels of the non-warped image starting at the bottom row of the non-warped image, the control circuit 310 may find the lowest pixel that indicates a glare source before detecting other higher glare sources. The lowest pixel that indicates a glare source is an important parameter for determining the shade position to which to control the motorized window treatments to prevent glare on the task surface. This allows allow the control circuit 310 to minimize the amount of processing that is needed to determine the shade control command to prevent glare in the room.

When processing the non-warped images to determine if a glare condition exists, the control circuit 310 may be configured to determine if an absolute glare condition exists and/or a relative glare condition (e.g., a contrast glare condition) exists. The control circuit 310 may be configured to determine that an absolute glare condition exists if the absolute light level (e.g., absolute intensity) of a pixel exceeds an absolute glare threshold (e.g., approximately 10,000 cd/m²). The control circuit 310 may be configured to determine that a relative glare condition exists if the relative light level as compared to a background light level (e.g., the difference between the absolute light level of the pixel and a background light level) exceeds a relative glare threshold (e.g., approximately 4,000 cd/m²). If the control circuit 310 detects that either an absolute glare condition exists or a relative glare condition exists, the control circuit may stop processing the non-warped image and move to control the motorized window treatment(s) to remove the glare condition. For example, the motorized window treatments(s) may remove the glare condition by determining a shade position based on the location of the glare condition. The thresholds may be adjustable to adjust a sensitivity of the visible light sensor 300. For example, the thresholds may be adjusted by a user during configuration of the visible light sensor 300.

To determine if a relative glare condition exists, the control circuit 310 may determine a background light level from the non-warped image (e.g., a baseline). The background light level may be a value representative of a luminance of the background of the non-warped image. For example, the background light level may be a percentile luminance of the non-warped image (e.g., a 25^(th) percentile luminance). The 25^(th) percentile luminance may be a luminance, where 25% of the pixels of the non-warped image are darker than the 25^(th) percentile luminance.

When the control circuit 310 has determined that a glare condition exists, the control circuit 310 may process the pixel to determine a profile angle of the glare source. For example, each pixel of the image may be characterized by a value of the profile angle. The values for the profile angle may be stored in the memory 312. The control circuit 310 may retrieve the appropriate profile angle based on the processed pixel. In addition, the profile angle may be determined and/or calculated from the data of the image. The control circuit 310 may determine a position to which to control the motorized window treatments using the profile angle (e.g., as shown in Equations 2 and/or 3 above). In addition, the control circuit 310 may transmit the profile angle to another device (e.g., the system controller 110), which may determine a position to which to control the motorized window treatments to avoid a glare condition in the room.

FIG. 4 is a simplified flowchart of an example glare detection procedure 400. The glare detection procedure 400 may be executed periodically by a control circuit of a visible light sensor (e.g., the control circuit 310 of the visible light sensor 300) at 410. At 412, the control circuit may retrieve an image (e.g., a non-warped image). For example, the control circuit may record one or more images and process the images to produce a non-warped image. Additionally or alternatively, the control circuit may retrieve one or more images (e.g., non-warped images) from memory at 412. At 414, the control circuit may begin processing a portion of the image. For example, the control circuit may begin processing the bottom portion of the image (e.g., the bottom row of pixels in the image). At 416, the control circuit may process a pixel of the image to determine if a glare condition (e.g., an absolute glare condition and/or a relative glare condition) exists. If the control circuit does not determine that a glare condition exists at 418 and the control circuit is not done processing the present image at 420, the control circuit may move to the next pixel at 422 and then process the next pixel at 416 to determine if a glare condition exists. If the control circuit determines that a glare condition exists at 418, the control circuit may process the present pixel at 424 to allow for control of a motorized window treatment to prevent the glare condition, before the procedure 400 exits. For example, the control circuit may determine a profile angle of the glare source in the image and/or determine a position to which to control the motorized window treatment to prevent the glare condition at 424. If the control circuit does not detect a glare condition before the control circuit is finished processing the image at 420, the procedure 400 may exit. Though the image processing may be described as being performed at the visible light sensor, the image processing may be performed at the system controller or another image processing device in the load control system.

FIG. 5A shows a flowchart of an example glare detection procedure 500 executed periodically by a control circuit of a visible light sensor (e.g., the control circuit 210 of the visible light sensor 200) at 510. At 512, the control circuit may retrieve an image. For example, the image may comprise a high-dynamic-range (HDR) image, which may be a composite of multiple low-dynamic-range (LDR) images (e.g., six LDR images) recorded by a camera of the visible light sensor. At 514, the control circuit may de-warp the retrieved image (e.g., if the visible light sensor has a fish-eye lens) to produce a non-warped image. For example, to produce the non-warped image, the control circuit may generate rows of constant profile angle from the warped image. At 516, the control circuit may determine a background luminance for the non-warped image. For example, the control circuit may calculate a percentile luminance (e.g., a 25^(th) percentile luminance L₂₅), which may be a value representative of a luminance of the background of the non-warped image (e.g., a baseline).

At 518, the control circuit may determine the luminance L_(PI) of the i^(th) pixel of the non-warped image (from 514). For example, the control circuit may start at one of the pixels on the bottom row of the non-warped image (e.g., at the left or right side of the bottom row), the first time that 518 is executed. If the retrieved image is an HDR image, the control circuit may retrieve the luminance L_(PI) of the i^(th) pixel from the data of the HDR image at 518. The control circuit may also calculate the luminance L_(PI) of the i^(th) pixel (e.g., using Equation 4 shown above) at 518.

If the calculated luminance L_(PI) is greater than a high luminance threshold L_(TH-HI) (e.g., approximately 10,000 cd/m²) at 520, the control circuit may determine that there is a glare condition present (e.g., an absolute glare condition) at 522. At 524, the control circuit may determine a profile angle A_(PI) for the i^(th) pixel (e.g., representing an approximate location of the glare source) using the row of the i^(th) pixel from the non-warped image. For example, the control circuit may recall the profile angle A_(PI) for the i^(th) pixel from memory and/or may calculate the profile angle A_(PI) using the data of the i^(th) pixel and/or other pixels of the image.

At 526, the control circuit may determine a shade position for preventing light from the glare source from exceeding a maximum penetration distance and/or preventing glare on a task surface based on the profile angle A_(PI) (e.g., using Equation 2 and/or Equation 3 shown above). The shade position for preventing light from the glare source from exceeding a maximum penetration distance and/or for preventing glare on the task surface may also be dependent upon the maximum penetration distance, a height of the task surface, and/or a distance of the task surface from the windows, which may be stored in memory. At 528, the control circuit may transmit a shade control command for controlling the position of motorized window treatments in the space to the determined shade position for preventing glare on the task surface (e.g., directly or via the system controller 110), before the glare detection procedure 500 exits. Alternatively, the control circuit may be configured to transmit the profile angle A_(PI) to the system controller 110, which may determine the shade position for preventing glare on the task surface and transmit the shade control command to the motorized window treatments. Though the image processing may be described as being performed at the visible light sensor, the image processing may be performed at the system controller or another image processing device in the load control system.

If the calculated luminance L_(PI) is not greater than the high luminance threshold L_(TH-HI) at 520, the control circuit may be configured to determine if the calculated luminance L_(PI) is less than a low luminance threshold L_(TH-LO) (e.g., approximately 4,000 cd/m²) at 530. If the calculated luminance L_(PI) is less than the low luminance threshold L_(TH-LO) at 530, the control circuit may decide not to process the i^(th) pixel of the non-warped image. If the control circuit is not done processing the pixels of the non-warped image at 532, the control circuit may move onto the next pixel (e.g., i=i+1) at 534 and may calculate the luminance L_(PI) of the next pixel of the non-warped image at 518. As previously mentioned, the control circuit may start at one of pixels on the bottom row of the non-warped image (e.g., at the left or right side of the bottom row). When the control circuit moves onto the next pixel at 534, the control circuit may move to the pixel adjacent to the previous pixel in the present row of pixels (e.g., to the left or the right of the previous pixel). When the control circuit has calculated the luminance for each pixel in a row, the control circuit may move up to the next row of pixels. In this way, the control circuit may step through multiple pixels in the non-warped image by starting at the bottom row and moving up through the rows of the image.

If the calculated luminance L_(PI) is not less than the low luminance threshold L_(TH-LO) at 530, the control circuit may calculate a contrast ratio C_(PI) based on the calculated luminance L_(PI) and the 25^(th) percentile luminance L₂₅ (e.g., C_(PI)=L_(PI)/L₂₅) at 536. If the contrast ratio C_(PI) is greater than a contrast threshold C_(TH) (e.g., approximately 15) at 538, the control circuit may determine that there is a glare condition present (e.g., a relative glare condition) at 522. The control circuit may then calculate a profile angle A_(PI) for the i^(th) pixel at 524, determine a shade position for preventing glare on the task surface based on the profile angle A_(PI) at 526, and transmit a shade control command for controlling the position of motorized window treatments in the space at 528, before the glare detection procedure 500 exits. Alternatively, the control circuit may use the calculated luminance L_(PI) of the i^(th) pixel and the luminance of neighboring pixels (e.g., the lowest luminance of the neighboring pixels) at 538 to calculate the contrast ratio C_(PI) at 536. For example, the neighboring pixels may be those pixels with a certain number of pixels from the i^(th) pixel (e.g., all pixels within five pixels from the i^(th) pixel).

When the control circuit has finished processing the pixels of the non-warped image at 532 without determining that a glare condition exists, the control circuit may determine that no glare condition exists at 540 and may transmit a shade control command for controlling the position of motorized window treatments at 528, before the glare detection procedure 500 exits. For example, if no glare condition exists, the control circuit may transmit a shade command for opening the motorized window treatments (e.g., to a fully-opened position or a visor position).

FIG. 5B shows a flowchart of another example glare detection procedure 550 executed periodically by a control circuit of a visible light sensor (e.g., the control circuit 210 of the visible light sensor 200) at 560. At 562, the control circuit may retrieve an image (e.g., an HDR image). At 564, the control circuit may de-warp the retrieved image (e.g., if the visible light sensor has a fish-eye lens) to produce a non-warped image (e.g., by generating rows of constant profile angle from the warped image). At 566, the control circuit may determine a background luminance L_(BG) for the non-warped image. For example, the control circuit may calculate a percentile luminance (e.g., a 25^(th) percentile luminance L₂₅), which may be a value representative of a luminance of the background of the non-warped image (e.g., a baseline).

At 568, the control circuit may determine a contrast luminance L_(C), which may represent the luminance of a glare source that may generate a contrast glare condition (e.g., a relative glare condition). For example, the control circuit may be configured to scale the background luminance L_(BG) by a contrast threshold C_(TH) (e.g., approximately 15) to generate the contrast luminance L_(C), e.g., L_(C)=C_(TH)·L_(BG). If the contrast luminance L_(C) is greater than a low luminance threshold L_(TH-LO) (e.g., approximately 4,000 cd/m²) and less than a high luminance threshold L_(TH-HI) (e.g., approximately 10,000 cd/m²) at 570, the control circuit may set a luminance threshold L_(TH) equal to the contrast luminance L_(C) at 572. Otherwise, the control circuit may set the luminance threshold L_(TH) equal to the high luminance threshold L_(TH-HI) at 574.

At 576, the control circuit may determine the luminance L_(PI) of the i^(th) pixel of the non-warped image (from 564) (e.g., by retrieving the luminance L_(PI) from the data of an HDR image and/or calculating the luminance L_(PI)). For example, the control circuit may start at one of the pixels on the bottom row of the non-warped image (e.g., at the left or right side of the bottom row), the first time that 576 is executed. If the calculated luminance L_(PI) is greater than the luminance threshold L_(TH) at 578, the control circuit may determine that there is a glare condition present at 580. At 582, the control circuit may calculate a profile angle A_(PI) for the i^(th) pixel (e.g., representing an approximate location of the glare source) using the row of the i^(th) pixel from the non-warped image. At 584, the control circuit may determine a shade position for preventing light from the glare source from exceeding a maximum penetration distance and/or preventing glare on a task surface based on the profile angle A_(PI) (e.g., using Equation 2 and/or Equation 3 shown above). The shade position for preventing light from the glare source from exceeding a maximum penetration distance and/or for preventing glare on the task surface may be dependent upon the maximum penetration distance, a height of a task surface, and/or a distance of a task surface from the windows, which may be stored in memory. At 586, the control circuit may transmit a shade control command for controlling the position of motorized window treatments in the space to the determined shade position for preventing glare on the task surface (e.g., directly or via the system controller 110), before the glare detection procedure 550 exits. Alternatively, the control circuit may be configured to transmit the profile angle A_(PI) to the system controller 110, which may determine the shade position for preventing glare on the task surface and transmit the shade control command to the motorized window treatments. Though the image processing may be described as being performed at the visible light sensor, the image processing may be performed at the system controller or another image processing device in the load control system.

If the control circuit is not done processing the pixels of the non-warped image at 588, the control circuit may move onto the next pixel (e.g., i=i+1) at 590 and may calculate the luminance L_(PI) of the next pixel of the non-warped image at 576. As previously mentioned, the control circuit may start at one of pixels on the bottom row of the non-warped image (e.g., at the left or right side of the bottom row). When the control circuit moves onto the next pixel at 590, the control circuit may move to the pixel adjacent to the previous pixel in the present row of pixels (e.g., to the left or the right of the previous pixel). When the control circuit has calculated the luminance for each pixel in a row, the control circuit may move up to the next row of pixels. In this way, the control circuit may step through multiple pixels in the non-warped image by starting at the bottom row and moving up through the rows of the image.

When the control circuit has finished processing the pixels of the non-warped image at 588 without determining that a glare condition exists, the control circuit may determine that no glare condition exists at 592 and may transmit a shade control command for controlling the position of motorized window treatments at 586, before the glare detection procedure 550 exits. For example, if no glare condition exists, the control circuit may transmit a shade command for opening the motorized window treatments (e.g., to a fully-opened position or a visor position).

FIG. 6 is a simplified flowchart of a background luminance procedure 600. The background luminance procedure 600 may determine a value representative of a luminance of the background of an image (e.g., a non-warped image). The background luminance procedure 600 may be executed by a control circuit of a visible light sensor (e.g., the control circuit 310 of the visible light sensor 300), a system controller, or another image processing device at 610. For example, the background luminance procedure 600 may be executed at 516 of the glare detection procedure 500 shown in FIG. 5A and/or at 566 of the glare detection procedure 550 shown in FIG. 5B to calculate a 25^(th) percentile luminance L₂₅ of the non-warped image. At 612, the control circuit may reorder the pixels of the image in order from darkest to lightest. At 614, the control circuit may find the pixel that is a predetermined percentage (e.g., approximately 25%) of the way from the darkest pixel to the brightest pixel. For example, if the image has a total number N_(P) of pixels, the control circuit may count through the reordered pixels (from darkest to brightest) until finding the pixel at number N₂₅, where N₂₅=0.25·N_(P). At 616, the control circuit may calculate the luminance of the pixel (e.g., using the color of the pixel at number N₂₅) to determine the 25^(th) percentile luminance L₂₅. Alternatively, the control circuit may calculate the luminance of a different numbered pixel to set as the luminance of the background. The background luminance procedure 600 may exit at 618.

While the glare detection procedures 400, 500 of FIGS. 4 and 5 are described herein with the control circuit processing the non-warped image starting at the bottom portion (e.g., a bottom row) and working up through the rows of the image, the procedure may be reversed when the room 102 includes motorized window treatments that are bottom-up window treatments, e.g., the window treatment fabric moves from the bottom of the window to the top to cover the window. For example, when the motorized window treatments are bottom-up window treatments, the glare detection procedures 400, 500 may process the image starting at the top portion (e.g., a top row) and work down through the rows of the image, e.g., until a glare source is detected.

FIG. 7A is a sequence diagram of an example glare prevention procedure 700. As seen in FIG. 7A the glare prevention procedure 700 may be performed by a visible light sensor 702 (e.g., the visible light sensor 182, 300) and a motorized window treatment 704 (e.g., the motorized roller shade 220). At 710, the visible light sensor 702 may record an image of the outside of a room and/or building. At 712, the visible light sensor may process the image to detect a glare condition. For example, the detection of a glare condition may include calculating the luminance L_(PI) of a pixel in the image and comparing them to luminance thresholds (e.g., 520, 522, 530, 536, and/or 538 of FIG. 5A).

If a glare condition is detected, the visible light sensor 702 may determine a profile angle of the glare condition at 714. As described herein, the profile angle may define the position of the glare source outside of a window (e.g., the window 202 in FIG. 2). The profile angle may be determined based on the location of the detected glare source (e.g., a pixel in the image recorded at 710). The visible light sensor 702 may comprise a lookup table to determine the profile angle. For example, the lookup table may provide an indication of the profile angle based on the location (e.g., a pixel in the image recorded at 710) of the detected glare source.

At 716, the visible light sensor 702 may determine the shade position for the motorized window treatment 704. The shade position may prevent a glare condition from affecting a room (e.g., the room 102 and/or the space 200). For example, the shade fabric may be positioned such that the shade fabric blocks light from the glare source represented by the pixel where the glare was detected. At 718, the shade position may be transmitted to the motorized window treatment 704. After receiving the shade position, the motorized window treatment may move the shade fabric to the indicated position at 720.

FIG. 7B is a sequence diagram of an example glare prevention procedure 750. As seen in FIG. 7B, the glare prevention procedure 750 may be performed by a visible light sensor 752 (e.g., the visible light sensor 182, 300), a system controller 754 (e.g., the system controller 110), and a motorized window treatment 756 (e.g., the motorized roller shade 220). At 758, the visible light sensor 752 may record an image of the outside of a room and/or building. At 760, the visible light sensor may process the image to detect a glare condition. For example, the detection of a glare condition may include calculating the luminance L_(PI) of a pixel in the image and comparing them to luminance thresholds (e.g., 520, 522, 530, 536, and/or 538 of FIG. 5A).

If a glare condition is detected, the visible light sensor 752 may determine a profile angle of the glare condition at 762. As described herein, the profile angle may define the position of the glare source outside of a window (e.g., the window 202 in FIG. 2). The profile angle may be determined based on the location of the detected glare source (e.g., a pixel in the image recorded at 758). The visible light sensor 752 may comprise a lookup table to determine the profile angle. For example, the lookup table may provide an indication of the profile angle based on the location (e.g., a pixel in the image recorded at 758) of the detected glare source.

At 764, the visible light sensor 752 may transmit the profile angle to the system controller 754 (e.g., the system controller 110). At 766, the system controller 754 may determine a shade position for the motorized window treatment 756. For example, the shade fabric may be positioned such that the shade fabric blocks light from the glare source represented by the pixel where a glare was detected. At 768, the system controller 754 may transmit the shade position to the motorized window treatment 756. After receiving the shade position, the motorized window treatment may move the shade fabric to the indicated position at 770. Though the visible light sensor 752 is shown as processing the image, the system controller 754 may also, or alternatively, perform the image processing after the visible light sensor 752 generates the image.

FIG. 8 is a simplified example of a non-warped image 800 used to detect a glare condition. As seen in FIG. 8, the image 800 may include one or more pixels (e.g., pixel 802, 804 and 806). The pixels may be organized in one or more pixel rows and/or one or more pixel columns. A visible light sensor (e.g., the visible light sensor 300) may retrieve the image 800 and process the image to determine if a glare condition exists. The visible light sensor may process the image to determine if a glare condition is present. This determination may include determining whether an absolute glare condition exist and/or a relative glare condition exists.

The visible light sensor may begin processing the first pixel in the bottom portion of the image 800. For example, the visible light sensor may begin processing the image 800 at pixel 802. The visible light sensor may determine the luminance of the pixel 802 to determine whether an absolute glare condition and/or a relative glare condition exists. If the visible light sensor determines that a glare condition (e.g., an absolute glare condition and/or a relative glare condition) does not exist, the visible light sensor may process the next pixel in the image (e.g., pixel 804).

The visible light sensor may continue processing the pixels in the image until the visible light sensor determines that a glare condition exists or finishes processing the image. For example, the visible light sensor may determine that a relative glare condition or an absolute glare condition exists at pixel 806 (e.g., the luminance of the pixel 806 is higher than a high luminance threshold or relative luminance threshold) and stop processing the image at pixel 806.

FIG. 9 is a block diagram illustrating an example system controller 900 (such as system controller 110, described herein). The system controller 900 may include a control circuit 902 for controlling the functionality of the system controller 900. The control circuit 902 may include one or more general purpose processors, special purpose processors, conventional processors, digital signal processors (DSPs), microprocessors, integrated circuits, a programmable logic device (PLD), application specific integrated circuits (ASICs), or the like. The control circuit 902 may perform signal coding, data processing, image processing, power control, input/output processing, or any other functionality that enables the system controller 900 to perform as described herein. The control circuit 902 may store information in and/or retrieve information from the memory 904. The memory 904 may include a non-removable memory and/or a removable memory. The non-removable memory may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of non-removable memory storage. The removable memory may include a subscriber identity module (SIM) card, a memory stick, a memory card, or any other type of removable memory.

The system controller 900 may include a communications circuit 906 for transmitting and/or receiving information. The communications circuit 906 may perform wireless and/or wired communications. The system controller 900 may also, or alternatively, include a communications circuit 908 for transmitting and/or receiving information. The communications circuit 906 may perform wireless and/or wired communications. Communications circuits 906 and 908 may be in communication with control circuit 902. The communications circuits 906 and 908 may include RF transceivers or other communications modules capable of performing wireless communications via an antenna. The communications circuit 906 and communications circuit 908 may be capable of performing communications via the same communication channels or different communication channels. For example, the communications circuit 906 may be capable of communicating (e.g., with a network device, over a network, etc.) via a wireless communication channel (e.g., BLUETOOTH®, near field communication (NFC), WIFI®, WI-MAX®, cellular, etc.) and the communications circuit 908 may be capable of communicating (e.g., with control devices and/or other devices in the load control system) via another wireless communication channel (e.g., WI-FI® or a proprietary communication channel, such as CLEAR CONNECT™).

The control circuit 902 may be in communication with an LED indicator 912 for providing indications to a user. The control circuit 902 may be in communication with an actuator 914 (e.g., one or more buttons) that may be actuated by a user to communicate user selections to the control circuit 902. For example, the actuator 914 may be actuated to put the control circuit 902 in an association mode and/or communicate association messages from the system controller 900.

Each of the modules within the system controller 900 may be powered by a power source 910. The power source 910 may include an AC power supply or DC power supply, for example. The power source 910 may generate a supply voltage V_(CC) for powering the modules within the system controller 900.

FIG. 10 is a block diagram illustrating an example control-target device, e.g., a load control device 1000, as described herein. The load control device 1000 may be a dimmer switch, an electronic switch, an electronic ballast for lamps, an LED driver for LED light sources, an AC plug-in load control device, a temperature control device (e.g., a thermostat), a motor drive unit for a motorized window treatment, or other load control device. The load control device 1000 may include a communications circuit 1002. The communications circuit 1002 may include a receiver, an RF transceiver, or other communications module capable of performing wired and/or wireless communications via communications link 1010. The communications circuit 1002 may be in communication with control circuit 1004. The control circuit 1004 may include one or more general purpose processors, special purpose processors, conventional processors, digital signal processors (DSPs), microprocessors, integrated circuits, a programmable logic device (PLD), application specific integrated circuits (ASICs), or the like. The control circuit 1004 may perform signal coding, data processing, power control, input/output processing, or any other functionality that enables the load control device 1000 to perform as described herein.

The control circuit 1004 may store information in and/or retrieve information from the memory 1006. For example, the memory 1006 may maintain a registry of associated control devices and/or control instructions. The memory 1006 may include a non-removable memory and/or a removable memory. The load control circuit 1008 may receive instructions from the control circuit 1004 and may control the electrical load 1016 based on the received instructions. For example, the electrical load 1016 may control a motorized window treatment (e.g., motorized window treatments 150). The load control circuit 1008 may send status feedback to the control circuit 1004 regarding the status of the electrical load 1016. The load control circuit 1008 may receive power via the hot connection 1012 and the neutral connection 1014 and may provide an amount of power to the electrical load 1016. The electrical load 1016 may include any type of electrical load.

The control circuit 1004 may be in communication with an actuator 1018 (e.g., one or more buttons) that may be actuated by a user to communicate user selections to the control circuit 1004. For example, the actuator 1018 may be actuated to put the control circuit 1004 in an association mode and/or communicate association messages from the load control device 1000.

Although features and elements are described herein in particular combinations, each feature or element can be used alone or in any combination with the other features and elements. For example, the functionality described herein may be described as being performed by a control device, such as a remote control device or a lighting device, but may be similarly performed by a hub device or a network device. The methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), removable disks, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).

While the methods described herein are described with reference to controlling motorized window treatments (e.g., the motorized window treatments 150 and/or the motorized roller shade 220) for preventing glare conditions, the methods may be used to control other types of control devices to prevent and/or alleviate glare conditions. For example, the methods described herein could be used to control the transmittance of controllable electrochromic glass and/or to adjust the positions of indoor or outdoor controllable louvers to prevent and/or alleviate glare conditions. 

What is claimed is:
 1. A sensor for detecting a location of a glare condition for controlling a shade position of a motorized window treatment, the sensor comprising: a visible light sensing circuit configured to record one or more images; and a control circuit configured to calculate a respective luminance of multiple pixels of a non-warped image, the control circuit configured to start at a first pixel on a first row of pixels at a bottom portion of the non-warped image and step through each of the multiple pixels on the first row before continuing to a next row of pixels to determine the respective luminance of each of the multiple pixels, the control circuit configured to detect the location of the glare condition from which the shade position of the motorized window treatment is controlled in response to the luminance of at least one of the multiple pixels; wherein the control circuit is configured to cease processing the non-warped image to avoid determination of the respective luminance for remaining pixels of the non-warped image upon detection of the glare condition.
 2. The sensor of claim 1, wherein the control circuit is configured to determine a background luminance representative of a luminance of a background of the non-warped image.
 3. The sensor of claim 2, wherein the control circuit is configured to determine the background luminance by reordering the pixels of the non-warped image from darkest to lightest and calculating the luminance of a pixel that is a predetermined percentage of the distance from the darkest pixel to the lightest pixel.
 4. The sensor of claim 3, wherein the predetermined percentage is 25%.
 5. The sensor of claim 2, wherein the control circuit is configured to detect the glare condition if the ratio of the luminance of a specific pixel to the background luminance is greater than a predetermined contrast threshold.
 6. The sensor of claim 1, wherein the control circuit is configured to detect the glare condition in response to the luminance of a specific pixel, calculate a profile angle of the glare source in response to the location of the specific pixel in the non-warped image, and determine the shade position to which to control a motorized window treatment in response to the profile angle.
 7. The sensor of claim 6, wherein the control circuit is configured to transmit a shade control command in response to the shade position determined from the profile angle.
 8. The sensor of claim 1, wherein the control circuit is configured to retrieve a high-dynamic-range image and de-warp the high-dynamic-range image to produce the non-warped image.
 9. The sensor of claim 8, wherein the control circuit produces the non-warped image by generating rows of constant profile angle from the warped image.
 10. The sensor of claim 1, wherein the control circuit is configured to detect the glare condition if the luminance of a specific pixel is greater than a luminance threshold.
 11. The sensor of claim 1, wherein the first row is the bottom row of the non-warped image.
 12. The sensor of claim 1, wherein the next row of pixels is immediately above the first row of pixels.
 13. The sensor of claim 1, wherein the control circuit is configured to calculate the respective luminance of each of the multiple pixels.
 14. The sensor of claim 1, wherein the image comprises an HDR image, and the control circuit is configured to retrieve the respective luminance of each of the multiple pixels from data of the HDR image.
 15. A sensor for detecting a location of glare condition from which a shade position of a motorized window treatment is controlled, the sensor comprising: a visible light sensing circuit configured to record one or more images; and a control circuit configured to calculate a background luminance of an image, wherein the background luminance is a value from which the glare condition is detected for controlling the shade position of the motorized window treatment, wherein the control circuit is configured to reorder pixels of the image from darkest to lightest, calculate a luminance of a first pixel that is a predetermined percentage of the distance from the darkest pixel to the lightest pixel, and set the luminance of the first pixel as the background luminance; wherein the control circuit is configured to detect the location of the glare condition when a ratio of the luminance of a second pixel to the background luminance is greater than a predetermined contrast threshold.
 16. The sensor of claim 15, wherein the predetermined percentage is 25%.
 17. A method for controlling a shade level of a motorized window treatment, the method comprising: receiving an image of a view outside of a window on which the motorized window treatment is installed; processing multiple pixels of the image to identify a profile angle that defines a position of a glare source outside of the window; and controlling the shade level of the motorized window treatment based on the profile angle of the glare source.
 18. The method of claim 17, further comprising: determining a pixel that represents a glare condition; and retrieving the profile angle from a predefined lookup table in memory based on the determined pixel.
 19. The method of claim 17, wherein the shade level is controlled by wirelessly transmitting a digital message to the motorized window treatment that indicates the shade level.
 20. The method of claim 17, wherein the multiple pixels are processed to identify a contrast between a luminance of at least two pixels in the image.
 21. The method of claim 20, wherein the profile angle is identified when the contrast between the luminance of the at least two pixels is greater than a luminance threshold.
 22. The method of claim 17, further comprising: calculating the shade level of the motorized window treatment using the profile angle and a maximum penetration distance.
 23. The method of claim 17, further comprising: transmitting the profile angle prior to controlling the shade level. 